Questions tagged [weather]

Weather means the atmospheric conditions, including wind, temperature and precipitation, in a specific area at a specific time.

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Does a plane's service ceiling vary with season/temperature?

Aircraft use barometric altitude, e.g. FL300 is the barometric altitude of 30,000 ft MSL. In winter however, FL300 is actually lower than the absolute altitude of 30,000 ft because of a cold and ...
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6 votes
1 answer
566 views

How to determine the base of stratus clouds? [closed]

For cumulus clouds this applies Calculate the 'spread,' where you're taking the current surface temperature and subtracting the dew point. Divide the spread by 4.4 (if temperatures are in °F) or 2.5 (...
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1 answer
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What are dry and saturated lapse rates values or ranges for a rising or lowering parcel of air in degrees Celsius?

Environmental lapse rate average is rounded to 2 degrees celsius per 1000 ft.(Note that environmental lapse rate varies through the day).What about parcel of air lapse rate.? Dry lapse rate is a ...
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1 vote
3 answers
140 views

Which countries use qfe field pressure?

I heard that acrobatic flight, Russians, Americans use qfe but is it always the case? Also why doesn't everyone use it? Isn't qfe field pressure better than qnh local pressure... Does a pilot ever use ...
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1 answer
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If while landing ,a surface inversion occured close to the ground would atc or atis know?

A change in temperature, pressure and many factors might happen in a surface inversion.Thus affecting landing performance and calculation.The local peessure might change suddenly as well...
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2 answers
113 views

Who gives us transition level when it varies?

Who gives us transition level when it varies? ATC, ATIS, any others?
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1 vote
1 answer
138 views

Why is rare to see landings from East to West at the AJU airport?

Every day at the Aracaju - SE, Brazil Airport (IATA: AJU, ICAO: SBAR) planes take off from West to East and lands from East to West. But in rare occasions they will land from West to East. I think it ...
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20 votes
3 answers
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Why would a pilot need to change their heading when flying through a cold front?

When doing my PPL written review there is a question, simply can't get my head wrapped around the reason why and have searched everywhere. It's definitely a very simple thing, however, I am missing ...
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1 answer
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When must ATC give wind variation and gust?

In connection with takeoff and landing, ATC will give the current wind direction and velocity to the pilot. In some cases, ATC will also report the variation in direction and/or current gust (max and ...
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-2 votes
3 answers
180 views

Difference between "pressure levels raising on warm days causing lower IA" and "TA being higher than IA on warm days" [duplicate]

IA: Indicated altitude TA: True altitude I have seen this picture before: Concept 1 and I understand this. On cold days, the pressure gradient is shorter which means the indicated altitude at a ...
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Is temperature inversion good or bad?

When there is temperature inversion, I heard that convection is suppressed and hence the layer of air is stable. But I also see the following questions when studying for my PAR: A pilot can expect a ...
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9 votes
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Is the pressure change due to volcanic activity a concern?

The recent eruption of the Hunga Tonga–Hunga Ha'apai sent a shockwave so massive that it got picked all over the world by weather stations. This is the pressure detected one in Italy (source), where ...
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Formation of Clouds in High Pressure Systems (Western Australia - Perth) [closed]

High pressure systems are normally correlated with stable atmospheric conditions with little to no cloud cover, but due to this minimal cloud cover, doesn't that open up the ocean / ground moisture to ...
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4 votes
1 answer
179 views

How far does the lightning detector work at an AWOS station, as reported in a METAR?

I noticed on my local airport's METAR that there was distant lightning to the east. I am near Kansas City. When I looked at radar, the only possible system that could produce lightning was in the St. ...
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5 votes
2 answers
296 views

What is considered to be a flight into known Icing?

I am aware that flight into known icing is prohibited if your aircraft is not suitable to fly in icing conditions (unless e.g.: FIKI,...). Given the following example I am wondering if it would be ...
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1 answer
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What is Tendency of RVR?

What does tendency of RVR (Runway Visual Range) mean and why down and up have the same values? This is from AWOS(Automated Weather Observing System)
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5 votes
1 answer
559 views

What does AO2A in the remarks of a METAR mean?

I am familiar with AO2 in the METAR remarks as described in this answer, which means the station is automated and has a precipitation discriminator. I have noticed sometimes there is AO2A in the ...
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3 votes
1 answer
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Will a jet flown on a parabolic arc reach its highest altitude on a warm day or a cold one?

In level flight, on cold days jet-powered planes can fly higher because the air is denser. However, at the same time the true airspeed is lower because of the denser air. At warmer temperatures a ...
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15 votes
3 answers
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Why would "hot gases" from a volcano damage helicopter rotors?

In the ongoing story about someone trying to rescue dogs from a volcano with a drone, I keep seeing variations of this claim repeated: Spanish authorities have dropped food down to the dogs with ...
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1 vote
1 answer
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Station pressure vs. reported altimeter

I must be missing something big. Page 12-5 of the PHAK tells me that a station at 5,000 feet above sea level would convert its 24.92 pressure reading to 29.92. I understand that this helps to track ...
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11 votes
4 answers
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Why are pressure levels raised on warm days?

As I'm studying for the PPL knowledge exam, I had the following note: Pressure levels are raised on warm days and the indicated altitude is lower than true altitude. (source: AOPA) But I don't quite ...
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What is inflated wind speed?

According to NOAA, inflated wind speed is "the true wind speed (in knots) adjusted to improve forecasts of higher wind speeds. Wind speeds greater than the mean wind speed observed are increased, ...
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0 votes
2 answers
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Best way to forecast density altitude?

Let's say I'm planning a day trip from a low elevation home base to a warm, mountainous location. I wake up early, check the weather, do performance calculations based on current METARs, and decide to ...
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2 votes
2 answers
393 views

Why is the minimum for VFR 1000/3 while there are VFR weather minimums for every single airspace?

It seems like I have a concept error here. I don't understand why "the VFR min is 1000/3" when I think I would need to check in which airspace I am to then check for its respective weather ...
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10 votes
3 answers
1k views

Effect of heat and humidity on take off, descent, climb, and cruise

I am aware of this question, this resource (phak), and this resource that explains the science, but I am looking for a more straightforward answer. I am student pilot and there's a lot of literature ...
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1 vote
1 answer
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What kind of weather conditions would produce turbulence with an intensity of 90 feet per second?

This is the official documentation that we found regarding current commercial airplane design criteria; https://www.law.cornell.edu/cfr/text/14/25.341 It says the criteria for continuous turbulence is ...
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3 votes
1 answer
192 views

Why does the Winds Aloft ‘For Use Time’ start before the ‘Valid Time’?

Why is it that a winds aloft forecast normally has a "valid time" that comes in the middle of the "for use" time range? Why don't they just state the valid time as the beginning of ...
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1 vote
1 answer
85 views

What does Region @TOP mean on the aviationweather.gov website?

When looking at raw METAR data on the aviation weather center, "@TOP" appears in the text box where you can type identifiers. What does TOP mean?
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4 votes
2 answers
243 views

Do airliners get substantially different weather briefings from the rest of us?

Southwest Airlines flights were delayed and cancelled this week due to an outage in their third-party weather provider. I understand if they have a streamlined business process for getting weather ...
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0 votes
2 answers
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How can I calculate the "stability state" of air from a given set of data?

I would like to know the answer for the above question, it is about how to find whether atmosphere is stable or unstable using DALR (dry adiabatic lapse rate), SALR (saturated adiabatic lapse rate) ...
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10 votes
1 answer
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What is the red barb for in the NOAA weather briefing?

Wind barbs are well-defined symbols, but I noticed in my WX briefing that there are now occasional red barbs in the chart. The red appears on both the 5kt and 10kt barbs, and sometimes for largest ...
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10 votes
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Can gusts be reported as lower than wind speed?

KADS 072350Z 31030G20KT 13SM SKC 24/02 A2980 I’ve never seen a negative gust factor before. Is that a real thing (and if so, what does it mean), or did someone just make a typo?
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2 votes
1 answer
114 views

When was the last time the US Standard Atmosphere 1976 was updated?

I imagine due to slight changes in Earth's atmosphere or more accurate instrumentation it's been updated at least once, but also because it's understood to be a less precise model we might not have ...
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1 vote
1 answer
114 views

How to get an accurate time of arrival to the en-route alternate airport during flight planning?

I was thinking about accurate criteria of selecting en-route alternate (ERA) weather from ground (planning stage) especially for ERA 3% contingency flight plan. As we all know we should care about one ...
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3 votes
2 answers
1k views

Can I derive the wind speed and direction? [duplicate]

If I know the IAS and GS (with directional components) of an aircraft, can I derive the wind speed and direction? I'm working on an application that simulates the flight of an aircraft. Another ...
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0 votes
1 answer
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What are the Requirements for the implimentation of Low Visibility Procedures at an airport?

So I was wondering if the RVR at an airport is reported above CAT I conditions for eg 1400 Meters etc but the Visibility is 50 to 100 Meters then would the pilots carry out non instrument approach or ...
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5 votes
1 answer
306 views

Why are the airport pressure values for "altitude" (inHg) and "sea level" (mb) slightly different on the NOAA web sites?

If one looks, for example, at the NOAA web site for Denver International Airport we see (at the time of posting this question) the Pressure/Altimeter is 29.78 inHg, the Pressure/sea level is 1006.1 mb ...
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1 vote
0 answers
59 views

A scenario question regarding meteorology

In the image attached, I’m struggling to find out why the answer is the way it is; maybe is me not being able to visualise it, but some help would be greatly appreciated.
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2 votes
1 answer
95 views

What causes Gusty winds? ( Meteorlogy) [closed]

I was wondering why winds can become gusty. I know that gusty winds tend to be related with frontal passage. Thanks : )
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2 votes
3 answers
282 views

What weather should we expect when temperature and dew point are similar?

What should i expect during my flight planning when i see both temperature and dew point are the same? I understand there will be fog but what else? could it mean icing? any difference between 20/20 ...
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1 vote
1 answer
116 views

Why is cloud base estimation taught in Fahrenheit?

I've seen the formula for estimating cloud base consistently presented using Fahrenheit temperature and dewpoint (for example, see PHAK 12-14; Jeppesen also teaches it this way): $$ \mathrm{cloud\:...
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1 vote
2 answers
250 views

How can I calculate ambient air pressure from flight data?

I am playing around with data collected during a flight. I would like to find out the (real, not ISA) ambient air pressure for each data point, since it is not reported in the spread sheet containing ...
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2 votes
1 answer
112 views

How can air stability be predicted?

After several weeks of being grounded due to low clouds, I was looking forward to the cool air, clear skies, high pressure and light winds that arrived this morning as forecasted. However, there is an ...
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0 votes
1 answer
235 views

What is the difference between the WSUSnn IDs used in convective SIGMETs?

When NOAA issues a convective SIGMET, it falls under one of three bulletin IDs: WSUS31, WSUS32, or WSUS33. Below are three examples from the current forecast. WSUS31: ...
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1 vote
1 answer
537 views

What is the difference between mist and haze in terms of relative humidity?

I am an aviation meteorologist and I struggle to distinguish the two of them.
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0 votes
1 answer
632 views

Where can I listen online to live VOLMET broadcasts?

Are there sites that stream live VOLMET broadcasts? I need to listen to the format but haven't have the time to put together an amateur radio.
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37 votes
2 answers
8k views

What do pilots landing on aircraft carriers do when the ship is not visible due to weather?

Say an aircraft takes off of a carrier to do a mission somewhere, and upon returning to the carrier the pilot comes to find that a thick layer of fog has formed just above the surface of the water in ...
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0 votes
2 answers
317 views

Does DA/DH refers to ceiling?

If airport is reporting FEW001 or SCT001 and RVR is above 600m, does it means that there will be no LVO because ceiling is defined as more than 4/8 and DA/DH will be more than 100ft because DA/DH is ...
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1 vote
1 answer
64 views

Are AWOS data open for commercial use? [closed]

I 've found out this great website where you can get historical AWOS weather data. I would like to use it for a commercial application but I don't find any data license. Do you know if the AWOS data ...
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1 vote
1 answer
112 views

Where is there an FAA source that states that squall lines are non-frontal?

There's a question in the FAA commercial question bank that indicates that squall lines are nonfrontal, and the reference for the question points to the Aviation Weather Advisory Circular. The word, &...
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